Metathesis catalysts have been previously described by for example, U.S. Pat. Nos. 5,312,940, 5,342,909, 5,728,917, 5,750,815, 5,710,298, and 5,831,108 and PCT Publications WO 97/20865 and WO 97/29135 which are all incorporated herein by reference. These publications describe well-defined single component ruthenium or osmium catalysts that possess several advantageous properties. For example, these catalysts are tolerant to a variety of functional groups and generally are more active than previously known metathesis catalysts. Recently, the inclusion of an N-heterocyclic carbene (NHC) ligand, such as an imidazolidine or triazolylidene ligand as described in U.S. application Ser. Nos. 09/539,840, 09/576,370 and PCT Publication No. WO 99/51344, the contents of each of which are incorporated herein by reference, in these metal-carbene complexes has been found to improve the already advantageous properties of these catalysts. In an unexpected and surprising result, the shift in structure from the well-established penta-coordinated catalyst structure to the hexacoordinated catalyst structure has been found to significantly improve the properties of the catalyst. For example, these hexacoordinated catalysts of the present invention exhibit increased activity and selectivity not only in ring closing metathesis (xe2x80x9cRCMxe2x80x9d) reactions, but also in other metathesis reactions including cross metathesis (xe2x80x9cCMxe2x80x9d) reactions, reactions of acyclic olefins, and ring opening metathesis polymerization (xe2x80x9cROMPxe2x80x9d) reactions.
The present invention relates to novel hexacoordinated metathesis catalysts and to methods for making and using the same. The inventive catalysts are of the formula 
wherein:
M is ruthenium or osmium;
X and X1 are the same or different and are each independently an anionic ligand;
L, L1xe2x80x2 and L2 are the same or different and are each independently a neutral electron donor ligand, wherein at least one L, L1xe2x80x2 and L2 is an N-heterocyclic carbene ligand; and,
R and R1 are each independently hydrogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthio, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl. Optionally, each of the R or R1 substituent group may be substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, and aryl which in turn may each be further substituted with one or more groups selected from a halogen, a C1-C5 alkyl, C1-C5 alkoxy, and phenyl. Moreover, any of the catalyst ligands may further include one or more functional groups. Examples of suitable functional groups include but are not limited to: hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen.
In preferred embodiments, L2 and L1xe2x80x2 are pyridine and L is a phosphine or an N-heterocyclic carbene ligand. Examples of N-heterocyclic carbene ligands include: 
wherein R, R1 R6, R7, R8, R9, R10 and R11 are each independently hydrogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthio, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl. Optionally, each of the R, R1 R6, R7, R8, R9, R10 and R11 substituent group may be substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, and aryl which in turn may each be further substituted with one or more groups selected from a halogen, a C1-C5 alkyl, C1-C5 alkoxy, and phenyl. Moreover, any of the catalyst ligands may further include one or more functional groups. Examples of suitable functional groups include but are not limited to: hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen. The inclusion of an NHC ligand to the hexacoordinated ruthenium or osmium catalysts has been found to dramatically improve the properties of these complexes. Because the NHC-based hexacoordinated complexes are extremely active, the amount of catalysts that is required is significantly reduced.
The present invention generally relates to ruthenium and osmium carbene catalysts for use in olefin metathesis reactions. More particularly, the present invention relates to hexacoordinated ruthenium and osmium carbene catalysts and to methods for making and using the same. The terms xe2x80x9ccatalystxe2x80x9d and xe2x80x9ccomplexxe2x80x9d herein are used interchangeably.
Unmodified ruthenium and osmium carbene complexes have been described in U.S. Pat. Nos. 5,312,940, 5,342,909, 5,728,917, 5,750,815, and 5,710,298, all of which are incorporated herein by reference. The ruthenium and osmium carbene complexes disclosed in these patents all possess metal centers that are formally in the +2 oxidation state, have an electron count of 16, and are penta-coordinated. These catalysts are of the general formula 
wherein:
M is ruthenium or osmium;
X and X1 are each independently any anionic ligand;
L and L1 are each independently any neutral electron donor ligand;
R and R1 are the same or different and are each independently hydrogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthio, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl. Optionally, each of the R or R1 substituent group may be substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, and aryl which in turn may each be further substituted with one or more groups selected from a halogen, a C1-C5 alkyl, C1-C5 alkoxy, and phenyl. Moreover, any of the catalyst ligands may further include one or more functional groups. Examples of suitable functional groups include but are not limited to: hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen.
The catalysts of the present invention are similar in that they are Ru or Os complexes; however, in these complexes, the metal is formally in the +2 oxidation state, and has an electron count of 18 and are hexacoordinated. These catalysts are of the general formula: 
wherein
M is ruthenium or osmium;
X and X1 are the same or different and are each independently any anionic ligand;
L, L1xe2x80x2, and L2 are the same or different and are each independently any neutral electron donor ligand;
R and R1 are the same or different and are each independently hydrogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthio, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl. Optionally, each of the R or R1 substituent group may be substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, and aryl which in turn may each be further substituted with one or more groups selected from a halogen, a C1-C5 alkyl, C1-C5 alkoxy, and phenyl. Moreover, any of the catalyst ligands may further include one or more functional groups. Examples of suitable functional groups include but are not limited to: hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen.
The hexacoordinated complex provides several advantages over the well-known pentacoordinated complexes. For example, the hexacoordinated complexes have greater air stability in the solid state because they are coordinatively saturated. Due to the lability of the additional ligand, e.g. pyridines, the complexes initiate faster than the phosphine based pentacoordinated species. Slow initiation means that only a small amount of complex is actually catalystically active thereby wasting much of the added complex. With faster initiators, catalyst loading is lowered. Further, and without being bound by theory, it is believed that the slower propogation of the hexacoordinated complexes, due to the re-binding of the labile ligands relative to the phosphines, translates to lower polydisperity. Moreover, the coordinatively saturated species crystallize better than their pentacoordinated counterparts. In addition, due to the lability of the ligands in the hexacoordinated complexes (e.g. pyridines and chlorines), these complexes allow access to previously inaccessible complexes and provide with higher purity certain complexes that can be obtained through different routes. For example, the pentacoordinated benzylidene with triphenylphosphine as its phosphine ligand can be prepared in higher yield and with greater purity using the hexacoordinated complex. The pentacoordinated benzylidene with P(p-CF3C6H4)3 as its phosphine ligand is inaccessible through existing routes. Without being bound by theory, it is believe that this is because it would require the substitution of a stronger donor ligand with a weaker donor ligand. Substitution of the anionic ligands of the hexacoordinated complexes is much more rapid than with the corresponding pentacoordinated species (e.g. phosphine bound). Without being bound by theory, it is believed that this results from the requirement of ligand dissociation before anionic ligand substitution. Thus complexes with fast dissociation of their neutral electron donor ligands will undergo faster substitution.
The catalysts of the invention are also useful for ring-opening metathesis polymerization (ROMP), ring-closing metathesis (RCM), ADMET, and cross-metathesis. The synthesis and polymerization of olefins via these metathesis reactions can be found in, for example, U.S. application Ser. No. 09/891,144 entitled: xe2x80x9cSynthesis of Functionalized and Unfunctionalized Olefins, filed Jun. 25, 2001, and U.S. application Ser. No. 09/491,800, now U.S. Pat. No. 6,306,988 the contents of each of which are incorporated herein by reference. Preferred embodiments of the catalysts of the invention possess at least one NHC ligand attached to the metal center, as illustrated by the following general formula: 
In preferred embodiments of the inventive catalysts, the R substituent is hydrogen and the R1 substituent is selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, and aryl. In even more preferred embodiments, the R1 substituent is phenyl or vinyl, optionally substituted with one or more moieties selected from the group consisting of C1-C5 alkyl, C1-C5 alkoxy, phenyl, and a functional group. In especially preferred embodiments, R1 is phenyl or vinyl substituted with one or more moieties selected from the group consisting of chloride, bromide, iodide, fluoride, xe2x80x94NO2, xe2x80x94NMe2, methyl, methoxy and phenyl. In the most preferred embodiments, the R1 substituent is phenyl or xe2x80x94Cxe2x95x90C(CH3)2. When R1 is vinyl, the catalyst is of the general formula: 
wherein M, L, L1, L1xe2x80x2, L2, X, X1, and R are as defined above. Rxe2x80x2 and Rxe2x80x3 are preferably independently hydrogen or phenyl but can be selected from any of the groups listed for R or R1.
In preferred embodiments of the inventive catalysts, X and X1 are each independently hydrogen, halide, or one of the following groups: C1-C20 alkyl, aryl, C1-C20 alkoxide, aryloxide, C3-C20 alkyldiketonate, aryldiketonate, C1-C20 carboxylate, arylsulfonate, C1-C20 alkylsulfonate, C1-C20 alkylthio, C1-C20 alkylsulfonyl, or C1-C20 alkylsulfinyl. Optionally, X and X1 may be substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, and aryl which in turn may each be further substituted with one or more groups selected from halogen, C1-C5 alkyl, C1-C5 alkoxy, and phenyl. In more preferred embodiments, X and X1 are halide, benzoate, C1-C5 carboxylate, C1-C5 alkyl, phenoxy, C1-C5 alkoxy, C1-C5 alkylthio, aryl, and C1-C5 alkyl sulfonate. In even more preferred embodiments, X and X1 are each halide, CF3CO2, CH3CO2, CFH2CO2, (CH3)3CO, (CF3)2(CH3)CO, (CF3)(CH3)2CO, PhO, MeO, EtO, tosylate, mesylate, or trifluoromethanesulfonate. In the most preferred embodiments, X and X1 are each chloride.
L, L1, L1xe2x80x2 and L2 may be any appropriate monodentate or multidentate neutral electron donor ligands. Multidentate neutral electron donor ligands include bidentate, tridentate, or tetradentate neutral electron donor ligands, for example. In preferred embodiments of the inventive catalysts, L, L1, L1xe2x80x2 and L2 are each independently selected from the group consisting of phosphine, sulfonated phosphine, phosphite, phosphinite, phosphonite, arsine, stibine, ether, amine, amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, and thioether, or any derivatives therefrom. At least one L, L1, L1xe2x80x2 and L2 may also be an N-heterocyclic carbene ligand. Preferred embodiments include complexes where both L1xe2x80x2 and L2 are either the same or different NHC ligands.
In preferred embodiments, at least one of L, L1, L1xe2x80x2 and L2 is a phosphine of the formula PR3R4R5, where R3, R4, and R5 are each independently aryl or C1-C10 alkyl, particularly primary alkyl, secondary alkyl or cycloalkyl. In the even more preferred embodiments, at least one of L, L1, L1xe2x80x2 and L2 is each selected from the group consisting of xe2x80x94P(cyclohexyl)3, xe2x80x94P(cyclopentyl)3, xe2x80x94P(isopropyl)3, and xe2x80x94P(phenyl)3. Even more preferably, at least one of L, L1, L1xe2x80x2 and L2 is an NHC ligand. A preferred embodiment include where L is an NHC, L1 is P(cyclohexyl)3 or xe2x80x94P(cyclopentyl)3, and L1xe2x80x2 and L2 are each heterocyclic ligands, optionally aromatic, or together form a bidenatate ligand. Preferably L1xe2x80x2 and L2 are each independently pyridine or a pyridine derivative.
Examples of NHC ligands include ligands of the general formulas: 
wherein R, R1, Rxe2x80x2, Rxe2x80x3, R6, R7, R8, R9, R10, and R11 are each independently hydrogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthio, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl. Optionally, each of the R, R1 R6, R7, R8, R9, R10, and R11 substituent group may be substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, and aryl which in turn may each be further substituted with one or more groups selected from a halogen, a C1-C5 alkyl, C1-C5 alkoxy, and phenyl. Moreover, any of the catalyst ligands may further include one or more functional groups. Examples of suitable functional groups include but are not limited to: hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen.
In preferred embodiments, R6, R7, R8 and R9 are independently selected from the group consisting of hydrogen, phenyl, or together form a cycloalkyl or an aryl optionally substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, aryl, and a functional group selected from the group consisting of hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen; and R10 and R11 are each is independently C1-C10 alkyl or aryl optionally substituted with C1-C5 alkyl, C1-C5 alkoxy, aryl, and a functional group selected from the group consisting of hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen.
In more preferred embodiments, R6 and R7 are both hydrogen or phenyl, or R6 and R7 together form a cycloalkyl group; R8 and R9 are hydrogen and R10 and R11 are each either substituted or unsubstituted aryl. Without being bound by theory, it is believed that bulkier R10 and R11 groups result in catalysts with improved characteristics such as thermal stability. In especially preferred embodiments, R10 and R11 are the same and each is independently of the formula: 
wherein:
R12, R13, and R14 are each independently hydrogen, C1-C10 alkyl, C1-C10 alkoxy, aryl, or a functional group selected from hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen. In especially preferred embodiments, R12, R13, and R14 are each independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, hydroxyl, and halogen. In the most preferred embodiments, R12, R13, and R14 are the same and are each methyl.
In these complexes, R6, R7, R8, and R9 are each independently hydrogen or a substituent selected from the group consisting Of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthio, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl. Iimidazolidine ligands are also referred to as imidizol-2-ylidene ligands.
Other examples of neutral electron donor ligands include ligands which are derived, for example, from unsubstituted or substituted heteroarenes such as furan, thiophene, pyrrole, pyridine, bipyridine, picolylimine, gamma-pyran, gamma-thiopyran, phenanthroline, pyrimidine, bipyrimidine, pyrazine, indole, coumarone, thionaphthene, carbazole, dibenzofuran, dibenzothiophene, pyrazole, imidazole, benzimidazole, oxazole, thiazole, dithiazole, isoxazole, isothiazole, quinoline, bisquinoline, isoquinoline, bisisoquinoline, acridine, chromene, phenazine, phenoxazine, phenothiazine, triazine, thianthrene, purine, bisimidazole and bisoxazole.
Examples of substituents are OH, halogen, C(O)ORs1, OC(O)Rs4, C(O)Rs2, nitro, NH2, cyano, SO3My, OSO3My, NR20SO3My, Nxe2x95x90Nxe2x80x94Rs2, C1-C12 alkyl, C2-C12 alkenyl, C1-C12 alkoxy, C3-C12 cycloalkyl, C3-C12 cycloalkenyl, C12-C11 heterocycloalkyl, C2-C11 heterocycloalkenyl, C6-C10 aryl, C6-C10 aryloxy, C5-C9 heteroaryl, C5-C9 heteroaryloxy, C7-C11 aralkyl, C7-C11 aralkyloxy, C6-C10 heteroaralkyl, C8-C11 aralkenyl, C7-C10 heteroaralkenyl, monoamino, diamino, sulfonyl, sulfonamide, carbamide, carbamate, sulfohydrazide, carbohydrazide, carbohydroxamic acid residue and aminocarbonylamide, in which Rs1 is hydrogen, My, C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C2-C11 heterocycloalkyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl or C6-C10 heteroaralkyl, Rs4 is hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C2-C11 heterocyloalkyl, C16-C10 aryl, C5-C19 heteroaryl, C7-C11 aralkyl or C6-C10 heteroaralkyl, and Rs2 and Rs20 are hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C3-C12 cycloalkenyl, C2-C11 heterocycloalkyl, C1-C11 heterocycloalkenyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl, C6-C10 heteroaralkyl, C8-C11 aralkenyl or C7-C10 heteroaralkenyl, and alkyl, alkenyl, alkoxy, cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, aryloxy, heteroaryl, heteroaryloxy, aralkyl, aralkyloxy, heteroaralkyl, aralkenyl and heteroaralkenyl in turn are unsubstituted or substituted by one of the above-mentioned substituents; and y is 1 and M is a monovalent metal or y is xc2xd and M is a divalent metal.
In the context of the description of the present invention, the terms metal and corresponding cations refer to an alkali metal, for example Li, Na or K, an alkaline earth metal, for example Mg, Ca or Sr, or Mn, Fe, Zn or Ag, and corresponding cations. Lithium, sodium and potassium ions, with their salts, are preferred. NH2, monoamino, diamino, carbamide, carbamate, carbohydrazide, sulfonamide, sulfohydrazide and aminocarbonylamide correspond preferably to a group R8 C(O)(NH)pN(R9)xe2x80x94, xe2x80x94C(O)(NH)pNR8R9, R8OC(O)(NH)pN(R9)xe2x80x94, R8R40NC(O)(NH)pN(R9)xe2x80x94, xe2x80x94OC(O)(NH)pNR8R9, xe2x80x94N(R40)C(O)(NH)pNR8R9, R8S(O)2(NH)pN(R9)xe2x80x94; xe2x80x94S(O)2(NH)pNR8R9; R8R40NS(O)2N(R9)xe2x80x94or xe2x80x94NR40S(O)2NR8R9, in which R8, R9 and R40 independently of one another are hydrogen, OH, C1-C12 alkyl, C1-C12 alkenyl, C3-C12 cycloalkyl, C3-C12 cycloalkenyl, C2-C11 heterocycloalkyl, C2-C11 heterocycloalkenyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C16 aralkyl, C8-C16 aralkenyl with C2-C6 alkenylene and C6-C10 aryl, C6-C15 heteroaralkyl, C6-C15 heteroaralkenyl, or di-C6-C10 aryl-C1-C6 alkyl, or R8xe2x80x2R9xe2x80x2N, in which R8xe2x80x2 and R9xe2x80x2 independently of one another are hydrogen, OH, SO3My, OSO3My, C1-C12 alkyl, C3-C12 cycloalkyl, C2-C11 heterocycloalkyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl, C6-C10 heteroaralkyl, C8-C16 aralkenyl with C2-C6 alkenylene and C6-C10 aryl, or di-C6-C10 aryl-C1-C6 alkyl, which are unsubstituted or substituted by one or more substituents from the group consisting of OH, halogen, C(O)ORs1, OC(O)Rs4, C(O)Rs2, nitro, NH2, cyano, SO3Zy, OSO3Zy, NR20SO3Zy, C1-C12 alkyl, C2-C12 alkenyl, C1-C12 alkoxy, C3-C12 cycloalkyl, C3-C12 cycloalkenyl, C2-C11 heterocycloalkyl, C2-C11 heterocycloalkenyl, C6-C10 aryl, C6-C10 aryloxy, C5-C9 heteroaryl, C5-C9 heteroaryloxy, C7-C11 aralkyl, C7-C11 aralkyloxy, C6-C10 heteroaralkyl, C8-C11 aralkenyl, C7-C10 heteroaralkenyl, monoamino, diamino, sulfonyl, sulfonamide, carbamide, carbamate, sulfohydrazide, carbohydrazide, carbohydroxamic acid residue and aminocarbonylamide, in which Rs1 is hydrogen, Zy, C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C2-C11 heterocycloalkyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl or C6-C10 heteroaralkyl, Rs4 is hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C2-C11 heterocycloalkyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl or C6-C10 heteroaralkyl, and Rs2is hydrogen C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C3-C12 cycloalkenyl, C2-C11 heterocycloalkyl, C2-C11 heterocycloalkenyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl, C6-C10 heteroaralkyl, C8-C11 aralkenyl or C7-C10 heteroaralkenyl, and alkyl, alkenyl, alkoxy, cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, aryloxy, heteroaryl, heteroaryloxy, aralkyl, aralkyloxy, heteroaralkyl, aralkenyl and heteroaralkenyl in turn are unsubstituted or substituted by one of the above-mentioned substituents; p is 0 or 1 and y is 1 and Z is a monovalent metal or y is xc2xd and Z is a divalent metal; or R8 and R9 or R8xe2x80x2 and R9xe2x80x2 or R8 and R40 in the case of xe2x80x94NR8R9 or xe2x80x94NR8xe2x80x2R9xe2x80x2 or R8R40Nxe2x80x94 together are tetramethylene, pentamethylene, xe2x80x94(CH2)2xe2x80x94Oxe2x80x94(CH2)2xe2x80x94, xe2x80x94(CH2)2xe2x80x94Sxe2x80x94(CH2)2xe2x80x94 or xe2x80x94(CH2)2xe2x80x94NR7xe2x80x94(CH2)2xe2x80x94, and R7 is H, C1-C6 alkyl, C7-C11 aralkyl, C(O)Rs2 or sulfonyl.
The sulfonyl substituent is, for example, of the formula R10xe2x80x94SO2xe2x80x94 in which R10 is C1-C12 alkyl, C3-C12 cycloalkyl, C2-C11 heterocycloalkyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl or C6-C10 heteroaralkyl which are unsubstituted or substituted by one or more substituents selected from the group consisting of OH, halogen, C(O)ORs1, OC(O)Rs4, C(O)Rs2, nitro, NH2, cyano, SO3Zy, OSO3Zy, NR20SO3Zy, C1-C12 alkyl, C2-C12 alkenyl, C1-C12 alkoxy, C3-C12 cycloalkyl, C3-C12 cycloalkenyl, C2-C11 heterocycloalkyl, C2-C11 heterocycloalkenyl, C6-C10 aryl, C6-C10 aryloxy, C5-C9 heteroaryl, C5-C9 heteroaryloxy, C7-C10 aralkyl, C6-C10heteroaralkyl, C8-C11 aralkenyl, C7-C10 heteroaralkenyl, monoamino, diamino, sulfonyl, sulfonamide, carbamide, carbamate, sulfonhydrazide, carbohydrazide, carbohydroxamic acid residue and aminocarbonylamide, in which Rs1 is hydrogen, Zy, C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C2-C11 heterocycloalkyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl or C6-C10 heteroaralkyl, Rs4 is hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C2-C11 heterocycloalkyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl or C6-C10heteroaralkyl, and Rs2 and R20 are hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C3-C12 cycloalkyl, C3-C12 cycloalkenyl, C2-C11 heterocycloalkyl, C2-C11 heterocycloalkenyl, C6-C10 aryl, C5-C9 heteroaryl, C7-C11 aralkyl, C6-C10 heteroaralkyl, C8-C11 aralkenyl or C7-C10 heteroaralkenyl, and alkyl, alkenyl, alkoxy, cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, aryloxy, heteroaryl, heteroaryloxy, aralkyl, heteroaralkyl, aralkenyl and heteroaralkenyl in turn are unsubstituted or substituted by one of the above-mentioned substituents; and y is 1 and Z is a monovalent metal or y is xc2xd and Z is a divalent metal. Preferred neutral electron donor ligands are derived, for example, from heteroarenes of the group 
A more preferred group of compounds is formed when L2 and L1xe2x80x2 independently of one another are pyridyl which is unsubstituted or substituted by one or more substituents from the group consisting Of C1-C12 alkyl, C2-C11 heterocycloalkyl, C5-C9 heteroaryl, halogen, monoamino, diamino and xe2x80x94C(O)H. Examples are 
Another preferred group of compounds is formed when L2 and L1xe2x80x2 together are bipyridyl, phenanthrolinyl, bithiazolyl, bipyrimidinyl or picolylimine which are unsubstituted or substituted by one or more sub stituents from the group consisting of C1-C12 alkyl, C6-C10 aryl and cyano, the substituents alkyl and aryl being in turn unsubstituted or substituted by one or more substituents from the group consisting of C1-C12 alkyl, nitro, monoamino, diamino and nitro- or diamino-substituted xe2x80x94Nxe2x95x90.Nxe2x80x94C6-C10 aryl. Examples are: 
Even more preferably, L2 and L1xe2x80x2 are each independently selected from the group consisting of: 
wherein R is selected from the group consisting of hydrogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthio, C1-C20 alkylsulfonyl and C1-C20 alkylsulfinyl. Optionally, the R group may be substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, and aryl which in turn may each be further substituted with one or more groups selected from a halogen, a C1-C5 alkyl, C1-C5 alkoxy, and phenyl. Moreover, any of the heterocycles may further include one or more functional groups. Examples of suitable functional groups include but are not limited to: hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen. Preferably R is selected from the group consisting of C1-C20 alkyl, aryl, ether, amine, halide, nitro, ester and pyridyl.
Preferably complexes 1-4 are used to make the preferred embodiments 5-29 of the inventive complex: 
wherein sIMES is 
Most preferably, L is an NHC, preferably an imidazolidine ligand, and L2 and L1xe2x80x2 are pyridines.
The carbene complexes of the invention may also be cumulated. For example, one aspect of the invention is a catalyst of the general structure: 
wherein M, L, L1, L1xe2x80x2, L2, X, X1, R and R1 are as defined above
In all of the above carbene complexes, at least one of L, L1, L1xe2x80x2, L2, X, X1, R and R1, may be linked to at least one other of L, L1, L1xe2x80x2, L2, X, X1, R and R1 to form a bidentate or multidentate ligand array.
Synthesis
In general, the inventive catalysts are made by contacting excess neutral electron donor ligand, such as a pyridine, with the previously described penta-coordinated metal carbene catalyst complex of the formula: 
wherein:
M, X, X1, L, L1, R and R1 are as previously defined; and wherein the third neutral electron donor ligand attaches to the metal center. Scheme 1 shows the general synthesis reaction for forming the inventive hexacoordinated metal carbene complexes: 
wherein:
M, X, X1, L, L1, L1xe2x80x2, L2, R and R1 are as previously defined.
The synthesis of a preferred embodiment is shown in Scheme 2: 
As shown by Schemes 1 and 2, in the presence of excess ligand L2, the pentacoordinated complex loses the L1 ligand and ligands L2 and L1xe2x80x2 attach to the metal center. Ligands L2 and L1xe2x80x2 may be the same compound, for example, pyridines (when excess pyridine is used), or may together form a bidentate ligand. Alternatively, L1 and L1xe2x80x2 may be the same, in which case, the pentacoordinated compound does not necessarily lose the L1 ligand in the presence of excess L2.
The inventive complex may also be a cumulated carbene complex of the general formulas: 
wherein M, X, X1, L, L1, L1xe2x80x2, L2, R and R1 are as previously defined. The synthesis of these compounds would follow Scheme 1 except that the starting compound would be a pentacoordinated vinylidene or pentacoordinated cumulene, respectively. The synthesis of preferred embodiments of the vinylidenes can be seen in Scheme 3: 
Other preferred compounds synthesized by the inventive method include where L2 and L1xe2x80x2 form a bidentate ligand: 
The inventive hexacoordinated catalyst complexes provide synthetic utility and utility in catalytic reactions. Without being bound by theory, these complexes contain substitutionally labile ligands, for example, pyridine and chloride ligands, and serve as a versatile starting material for the synthesis of new ruthenium metal carbene complexes. The chloride ligands are more labile than in the corresponding pentacoordinated phosphine-based complexes. As stated above, X and X1 are any anionic ligand. Preferably X and X1 are selected from the group consisting of chloride, bromide, iodide, Tp, alkoxide, amide, and thiolate. The pyridine ligands are more labile than the phosphines in the corresponding pentacoordinated phosphine-based complexes. Again, as stated above, L, L1, L1xe2x80x2, and L2 can be any neutral electron donor ligands, including a NHC ligand. Depending on the size of the ligand, one or two neutral ligands (in addition to the NHC) may bind to the metal center.
Interestingly, the inventive catalyst complexes may be used in both metathesis reactions or the formation of an NHC ligand based complex. As shown in Scheme 4, the hexacoordinated complex can lose a neutral electron donor ligand to produce the pentacoordinated catalyst complex. The reaction may also proceed the other way to produce a hexacoordinated complex in the presence of excess L2. 
The pentacoordinated complex may also lose the L1 ligand to form the metathesis active tetracoordinated species (Scheme 5): 
As shown in Scheme 5, the L1 ligand may also attach to a tetracoordinated species to form the pentacoordinated complex.
The tetracoordinated species may then initiate polymerization when in the presence of an olefin, as shown in Scheme 6, or may form the NHC-ligand based pentacoordinated complex when in the presence of a protected NHC-ligand (Scheme 7): 
The following structure NHCxe2x80x94Axe2x80x94B indicates generally the protected form of a N-Heterocyclic Carbene (NHC). 
It is also envisioned that the protected NHCxe2x80x94Axe2x80x94B may be of an unsaturated variety, such as 
In the above structures, A is preferably H and B may be selected from the group consisting of CCl3; CH2SO2Ph; C6F5; OR21; and N(R22)(R23), wherein R21 is selected from the group consisting of Me, C2H5, i-C3H7, CH2CMe3, CMe3, C6H11 (cyclohexyl), CH2Ph, CH2norbomyl, CH2norbomenyl, C6H5, 2,4,6-(CH3)3C6H2 (mesityl), 2,6-i-Pr2C6H2, 4-Mexe2x80x94C6H4 (tolyl), 4-Clxe2x80x94C6H4; and wherein R22 and R23 are independently selected from the group consisting of Me, C2H5, i-C3H7, CH2CMe3, CMe3, C6H11 (cyclohexyl), CH2Ph, CH2norbomyl, CH2norbornenyl, C6H5, 2,4,6-(CH3)3C6H2 (mesityl), 2,6-i-Pr2C6H2, 4-Me-C6H4 (tolyl), 4-Clxe2x80x94C6H4). This approach relates to the thermal generation of a NHC ligand from a stable (protected) NHC derivative with a release of a quantity of Axe2x80x94B. One of the more preferred methods to generate a reactive NHC ligand is to employ a stable carbene precursor where the Axe2x80x94B compound is also a reactive NHC ligand. A detailed description of the protected NHC and related methods of synthesis and use can be seen in U.S. Provisional Patent Application No. 60/278,311 and No. 60/288,680, the contents of each of which are incorporated herein by reference. The following structure for the sImesHCCl3 shows a preferred embodiment of a protected NHC ligand for use with the inventive hexacoordinated complexes: 
The NHC ligand based pentacoordinated complex may then lose the L ligand to form the metathesis active tetracoordinated species and proceed to initiate the polymerization reaction in the presence of an olefin (Scheme 8): 
It should also be noted that the hexacoordinated complex can undergo a ligand exchange such that the NHC replaces another neutral electron donor ligand resulting in an NHC ligand based hexacoordinated complex (Scheme 9): 
In all the above schemes and complexes M, X, X1, L, L1, L1xe2x80x2, L2, R, R1, R6, R7, R8, R9, R10, R11, and Ry are as previously defined.
The reaction of complex 1 with a large excess (xcx9c100 equiv) of pyridine results in a rapid color change from red to bright green, and transfer of the resulting solution to cold (xe2x88x9210xc2x0 C.) pentane leads to the precipitation of the bis-pyrdine adduct (ImesH2)(Cl)2 (C5H5N)2Ruxe2x95x90CHPh (31). Complex 31 can be purified by several washes with pentane and is isolated as an air-stable green solid that is soluble in CH2Cl2, benzene and THF. This procedure provides complex 31 in 80-85% yield and is easily carried out on a multigram scale.
Crystals suitable for X-ray crystal structure determination were grown by vapor diffusion of pentane into a saturated benzene solution of 31 at room temperature. The collection and refinement parameters for the crystallographic analysis are summarized in Table 1.
A labeled view of complex 31 is shown in FIG. 1 and representative bond lengths and bond angles are reported in Table 2:
Several structural isomers of the bis-pyridine adduct can be envisioned, but the solid-state structure reveals that the pyridines bind in a cis geometry, occupying the coordination sites trans to the benzylidene and the N-heterocyclic carbene ligand. The Ruxe2x95x90C(1) (benzylidene carbon) bond length of 1.873(4) xc3x85 is slightly longer than those in five-coordinate ruthenium olefin metathesis catalysts, including (Cl)2(PCy3)2Ruxe2x95x90CHPh [d(Ruxe2x95x90Cxcex1)=1.838(2) xc3x85] and complex 1 [d(Ruxe2x95x90Cxcex1)=1.835(2) xc3x85]. The elongated Euxe2x95x90Cxcex1 bond in 31 likely results from the presence of a trans pyridine ligand. The Ruxe2x80x94C(38) (N-heterocyclic carbene) bond length of 2.033(4) xc3x85 is approximately 0.05 xc3x85 shorter than that in complex 1, which is likely due to the relatively small size and moderate trans influence of pyridine relative to PCy3. The 0.15 xc3x85 difference in the Ruxe2x80x94C(1) and Ruxe2x80x94C(38) bond distances highlights the covalent nature of the former and the dative nature of the latter ruthenium-carbene bond. Interestingly, the two Ruxe2x80x94N bond distances differ by more than 0.15 xc3x85, indicating that the benzylidene ligand exerts a significantly larger trans influence than the N-heterocyclic carbene.
The kinetics of the reaction between complex 1 and pyridine was investigated in order to determine the mechanism of this ligand substitution. The reaction of complex 1 (0.88 M in toluene) with an excess of pyridine-d5 (0.18-0.69 M) is accompanied by a 150 nm red shift visible MLCT absorbance, and this transformation can be followed by UV-vis spectroscopy. The disappearance of starting material (502 nm) was monitored at 20xc2x0 C., and in all cases, the data fit first-order kinetics over five half-lives. A plot of kobs versus [C5D5N] is presented in FIG. 2. The data show an excellent linear fit (R2=0.999) even at high concentrations of pyridine, and the y-intercept of this line (1.1xc3x9710xe2x88x923) is very close to zero. The rate constant for phosphine dissociation (kB) in complex 1 has been determined independently by 31p magnetization transfer experiments, and at 20xc2x0 C., kB is 4.1xc3x9710xe2x88x925 sxe2x88x921. This value of kB places an upper limit on the rate of dissociative ligand exchange in 1, and the observed rate constants for pyridine substitution are clearly 3 orders of magnitude larger than kB. Taken together, these results indicate that the substitution of PCy3 with pyridine proceeds by an associative mechanism with a second-order rate constant of 5.7xc3x9710xe2x88x922Mxe2x88x921sxe2x88x921 at 20xc2x0 C. In marked contrast, displacement of the phosphine ligand of 1 with olefinic substrates (which is the initiation event in olefin metathesis reactions) occurs via a dissociative mechanism.
Initial reactivity studies of complex 31 revealed that both pyridine ligands are substitutionally labile. For example, benzylidene 31 reacts instantaneously with 1.1 equiv. of PCy3 to release pyridine and regenerate complex 1. This equilibrium can be driven back toward the pyridine adduct by addition of an excess of C5D5N, but it is readily reestablished by removal of the volatiles under vacuum.
The facile reaction of 31with PCy3 suggested that the pyridines may be displaced by other incoming ligands and it was discovered that reaction of the bis-pyridine complex with a wide variety of phosphines provides a simple and divergent route to new ruthenium benzylidenes of the general formula (ImesH2)(PR3)(Cl)2Ruxe2x95x90CHPh. The combination of 31 and 1.1 equiv. of PR3 results in a color change from green to red/brown and formation of the corresponding PR3 adduct. The residual pyridine can be removed under vacuum, and the ruthenium products are purified by several washes with pentane and/or by column chromatography. This ligand substitution works well for a variety of alkyl- and aryl-substituted phosphines including PPH3, PBn3, and P(n-Bu)3 to produce complexes 32, 33 and 34. 
Additionally, the para-substituted triphenylphosphine derivatives 35, 36 and 37 (containing para substituents CF3, Cl, and OMe, respectively) can be prepared using the inventive method. The synthetic accessibility of complex 35 is particularly remarkable, because P(p-CF3C6H4)3 is an extremely electron-poor phosphine ("khgr"=20.5 cmxe2x88x921) The triarylphosphine ruthenium complexes 32, 35-37 are valuable catalysts as they are almost 2 orders of magnitude more active for olefin metathesis reactions than the parent complex 1.
There appear to be both steric and electronic limitations on the incoming phosphine ligand in the pyridine substitution reaction. For example, complex 31 does not react with P(o-tolyl)3 to produce a stable product, presumably due to the prohibitive size of the incoming ligand. The cone angle of P(o-tolyl)3 is 194xc2x0, while that of PCy3 (one of the larger phosphines shown to successfully displace the pyridines of 31) is 170xc2x0. Additionally, the electron-poor phosphine P(C6F6)3 shows no reaction with 31, even under forcing conditions. This ligand has a significantly lower electron donor capacity ("khgr"=33.6 cmxe2x88x921) than P(p-CF3C6H4)3 ("khgr"=20.5 cmxe2x88x921) and also has a larger cone angle than PCy3 (xcex8=184xc2x0).
The methodology described herein represents a dramatic improvement over previous synthetic routes to the complexes (NHC)(PR3)(Cl)2Ruxe2x95x90CHPh. Earlier preparations of these compounds involved reaction of the bis-phosphine precursor (PR3)2(Cl)2Ruxe2x95x90CHPh with an NHC ligand. These transformations were often low yielding (particularly when the NHC was small), and required the parallel synthesis of ruthenium precursors containing each PR3 ligand. Furthermore, bis-phosphine starting materials containing PR3 ligands that are smaller and less electron-donating than PPh3 (xcex8=145xc2x0; "khgr"=13.25 cmxe2x88x921; pKa=2.73) cannot be prepared, placing severe limitations on the complexes that are available by the earlier preparation methods.
The chlorine ligands of 31 are also substantially labile relative to those in the parent complex 1. For example, 31 reacts quantitatively with NaI within 2 hours at room temperature to afford (ImesH2)(I)2 (C5H5N)Ruxe2x95x90CHPh (38). In contrast, the reaction between 1 and NaI takes approximately 8 hours to reach completion under identical conditions. Interestingly, 1H NMR spectroscopy reveals that the diiodide complex 38 contains only one pyridine ligand, while the analogous dichloride species 31 coordinates 2 equiv. of pyridine. The relatively large size of the iodide ligands and the lower electrophilicity at the metal center in 38 (as compared to 31) are both believed to contribute to the formation of a five-coordinate complex in this system.
Complex 31 also reacts quantitatively with KTp [Tp=tris(pyrazolyl)borate] within 1 h at 25xc2x0 C. to produce the bright green product Tp(ImesH2)(Cl)Ruxe2x95x90CHPh (39), while the analogous reaction between complex 1 and KTp is extremely slow. (The latter proceeds to less than 50% completion even after several days at room temperature). Removal of the solvents under vacuum followed by filtration and several washes with pentane and methanol provides 39 as an air and moisture stable solid. Preliminary 1H NMR studies also show that the combination of 31 with an excess of KOt-Bu produces the four-coordinate benzylidene, (ImesH2)xe2x80x94(OtBu)2Ruxe2x95x90CHPh (40), quantitatively within 10 min. at ambient temperature. In contrast, the reaction between 1 and KOt-Bu to form 40 does not proceed to completion, even after several days at 35xc2x0 C. Complex 40 may be considered a model for the 14-electron intermediate, (IMesH2)(Cl)2Ruxe2x95x90CHPh, involved in olefin metathesis reactions of 1.
The invention provides a high-yielding procedure for the preparation of (IMesH2)(Cl)2 (C5H5N)2Ruxe2x95x90CHPh (31) from (IMesH2)(Cl)2 (PCy3)Ruxe2x95x90CHPh (1). In contrast to the reaction of 1 with olefinic substrates, this ligand substitution proceeds by an associative mechanism. Complex 31 reacts readily with phosphines, providing access to new complexes discussed herein. Complex 31 also undergoes reaction with KOt-Bu, NaI, and KTp to provide new four-, five-, and six-coordinate ruthenium benzylidenes. The inventive methodology is useful for facilitating the development of new ruthenium olefin metathesis catalysts containing structurally diverse ligand arrays.
Olefin Metathesis
The inventive complexes are useful in olefin metathesis reactions, particularly for polymerization reactions. These catalysts can be used in various metathesis reactions, including but not limited to, ring-opening metathesis polymerization of strained and unstrained cyclic olefins, ring-closing metathesis of acyclic dienes, acyclic diene metathesis polymerization (xe2x80x9cADMETxe2x80x9d), self- and cross-metathesis reactions, alkyne polymerization, carbonyl olefination, depolymerization of unsaturated polymers, synthesis of telechelic polymers, and olefin synthesis.
The most preferred olefin monomer for use in the invention is substituted or unsubstituted dicyclopentadiene (DCPD). Various DCPD suppliers and purities may be used such as Lyondell 108 (94.6% purity), Veliscol UHP (99+% purity), B.F. Goodrich Ultrene(copyright) (97% and 99% purities), and Hitachi (99+% purity). Other preferred olefin monomers include other cyclopentadiene oligomers including trimers, tetramers, pentamers, and the like; cyclooctadiene (COD; DuPont); cyclooctene (COE, Alfa Aesar); cyclohexenylnorbornene (Shell); norbornene (Aldrich); norbornene dicarboxylic anhydride (nadic anhydride); norbornadiene (Elf Atochem); and substituted norbornenes including butyl norbornene, hexyl norbornene, octyl norbornene, decyl norbornene, and the like. Preferably, the olefinic moieties include mono-or disubstituted olefins and cycloolefins containing between 3 and 200 carbons. Most preferably, metathesis-active olefinic moieties include substituted or unsubstituted cyclic or multicyclic olefins, for example, cyclopropenes, cyclobutenes, cycloheptenes, cyclooctenes, [2.2.1]bicycloheptenes, [2.2.2]bicyclooctenes, benzocyclobutenes, cyclopentenes, cyclopentadiene oligomers including trimers, tetramers, pentamers, and the like; cyclohexenes. It is also understood that such compositions include frameworks in which one or more of the carbon atoms carry substituents derived from radical fragments including halogens, pseudohalogens, alkyl, aryl, acyl, carboxyl, alkoxy, alkyl- and arylthiolate, amino, aminoalkyl, and the like, or in which one or more carbon atoms have been replaced by, for example, silicon, oxygen, sulfur, nitrogen, phosphorus, antimony, or boron. For example, the olefin may be substituted with one or more groups such as thiol, thioether, ketone, aldehyde, ester, ether, amine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, phosphate, phosphite, sulfate, sulfite, sulfonyl, carbodiimide, carboalkoxy, carbamate, halogen, or pseudohalogen. Similarly, the olefin may be substituted with one or more groups such as C1-C20 alkyl, aryl, acyl, C1-C20 alkoxide, aryloxide, C3-C20 alkyldiketonate, aryldiketonate, C1-C20 carboxylate, arylsulfonate, C1-C20 alkylsulfonate, C1-C20 alkylthio, arylthio, C1-C20 alkylsulfonyl, and C1-C20 alkylsulfinyl, C1-C20 alkylphosphate, arylphosphate, wherein the moiety may be substituted or unsubstituted.
These olefin monomers may be used alone or mixed with each other in various combinations to adjust the properties of the olefin monomer composition. For example, mixtures of cyclopentadiene dimer and trimers offer a reduced melting point and yield cured olefin copolymers with increased mechanical strength and stiffness relative to pure poly-DCPD. As another example, incorporation of COD, norbornene, or alkyl norbornene co-monomers tend to yield cured olefin copolymers that are relatively soft and rubbery. The resulting polyolefin compositions formed from the metathesis reactions are amenable to thermosetting and are tolerant of additives, stabilizers, rate modifiers, hardness and/or toughness modifiers, fillers and fibers including, but not limited to, carbon, glass, aramid (e.g., Kevlar(copyright) and Twaron(copyright)), polyethylene (e.g., Spectra(copyright) and Dyneema(copyright)), polyparaphenylene benzobisoxazole (e.g., Zylon(copyright)), polybenzamidazole (PBI), and hybrids thereof as well as other polymer fibers.
The metathesis reactions may optionally include formulation auxiliaries. Known auxiliaries include antistatics, antioxidants (primary antioxidants, secondary antioxidants, or mixtures thereof), ceramics, light stabilizers, plasticizers, dyes, pigments, fillers, reinforcing fibers, lubricants, adhesion promoters, viscosity-increasing agents, and demolding enhancers. Illustrative examples of fillers for improving the optical physical, mechanical, and electrical properties include glass and quartz in the form of powders, beads, and fibers, metal and semi-metal oxides, carbonates (e.g. MgCO3, CaCO3), dolomite, metal sulfates (e.g. gypsum and barite), natural and synthetic silicates (e.g. zeolites, wollastonite, and feldspars), carbon fibers, and plastics fibers or powders.
The UV and oxidative resistance of the polyolefin compositions resulting from the metathesis reactions using the inventive carbene complex may be enhanced by the addition of various stabilizing additives such as primary antioxidants (e.g., sterically hindered phenols and the like), secondary antioxidants (e.g., organophosphites, thioesters, and the like), light stabilizers (e.g., hindered amine light stabilizers or HALS), and UV light absorbers (e.g., hydroxy benzophenone absorbers, hydroxyphenylbenzotriazole absorbers, and the like), as described in U.S. application Ser. No. 09/498,120, filed Feb. 4, 2000, the contents of which are incorporated herein by reference.
Exemplary primary antioxidants include, for example, 4,4xe2x80x2-methylenebis (2,6-di-tertiary-butylphenol) (Ethanox 702(copyright); Albemarle Corporation), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene (Ethanox 330(copyright); Albermarle Corporation), octadecyl-3-(3xe2x80x2,5xe2x80x2-di-tert-butyl-4xe2x80x2-hydroxyphenyl) propionate (Irganox 1076(copyright); Ciba-Geigy), and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)(Irganox(copyright) 1010; Ciba-Geigy). Exemplary secondary antioxidants include tris(2,4-ditert-butylphenyl)phosphite (Irgafos(copyright) 168; Ciba-Geigy), 1:11(3,6,9-trioxaudecyl)bis(dodecylthio)propionate (Wingstay(copyright) SN-1; Goodyear), and the like. Exemplary light stabilizers and absorbers include bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate (Tinuvin(copyright) 144 HALS; Ciba-Geigy), 2-(2H-benzotriazol-2-yl)-4,6-ditertpentylphenol (Tinuvino(copyright) 328 absorber; Ciba-Geigy), 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenyl (Tinuvin(copyright) 327 absorber; Ciba-Geigy), 2-hydroxy-4-(octyloxy)benzophenone (Chimassorb(copyright) 81 absorber; Ciba-Geigy), and the like.
In addition, a suitable rate modifier such as, for example, triphenylphosphine (TPP), tricyclopentylphosphine, tricyclohexylphosphine, triisopropylphosphine, trialkylphosphites, triarylphosphites, mixed phosphites, or other Lewis base, as described in U.S. Pat. No. 5,939,504 and U.S. application Ser. No. 09/130,586, the contents of each of which are herein incorporated by reference, may be added to the olefin monomer to retard or accelerate the rate of polymerization as required.
The resulting polyolefin compositions, and parts or articles of manufacture prepared therefrom, may be processed in a variety of ways including, for example, Reaction Injection Molding (RIM), Resin Transfer Molding (RTM) and vacuum-assisted variants such as VARTM (Vacuum-Assisted RTM) and SCRIMP (Seemann Composite Resin Infusion Molding Process), open casting, rotational molding, centrifugal casting, filament winding, and mechanical machining. These processing compositions are well known in the art. Various molding and processing techniques are described, for example, in PCT Publication WO 97/20865, the disclosure of which is incorporated herein by reference.
The metathesis reactions may occur in the presence or absence of a solvent. Examples of solvents that can be used in the polymerization reaction include organic, protic, or aqueous solvents, which are preferably inert under the polymerization conditions. Examples of such solvents include aromatic hydrocarbons, chlorinated hydrocarbons, ethers, aliphatic hydrocarbons, alcohols, water, or mixtures thereof. Preferred solvents include benzene, toluene, p-xylene, methylene chloride, dichloroethane, dichlorobenzene, chlorobenzene, tetrahydrofuran, diethylether, pentane, methanol, ethanol, water or mixtures thereof. More preferably, the solvent is benzene, toluene, p-xylene, methylene chloride, dichloroethane, dichlorobenzene, chlorobenzene, tetrahydrofuran, diethylether, pentane, methanol, ethanol, or mixtures thereof. Most preferably, the solvent is toluene, or a mixture of benzene and methylene chloride. The solubility of the polymer formed in the polymerization reaction will depend on the choice of solvent and the molecular weight of the polymer obtained.
The inventive complexes have a well-defined ligand environment that enables flexibility in modifying and fine-tuning the activity level, stability, solubility and ease of recovery of these catalysts. The solubility of the carbene compounds may be controlled by proper selection of either hydrophobic or hydrophilic ligands as is well known in the art. The desired solubility of the catalyst will largely be determined by the solubility of the reaction substrates and reaction products.
The inventive metal carbene complexes have shown a high rate of initiation allowing for most, if not all, of the complex added to the reaction to be consumed. Thus, less catalyst is wasted in the metathesis reaction. In contrast, the previous pentacoordinated initiators had a higher amount of extractibles (i.e. unpolymerized monomer) remaining after the reaction concluded. The rate of propagation is also slowed by the presence of the two pyridine ligands. The high rate of initiation and low rate of propagation yields polymers with narrow polydisperities relative to those achieved with the earlier pentacoordinated complexes. Moreover, it was determined that heat increases the rate of the initiation. Thermal initiation of the pentacoordinated complexes can be seen in U.S. Pat. No. 6,107,420, the contents of which are incorporated herein by reference. In general, the initiation and/or rate of the metathesis polymerization using the inventive catalysts is controlled by a method comprising contacting the inventive catalyst with an olefin and heating the reaction mixture. In a surprising and unexpected result, the Tmax for the thermal initiation of the inventive catalyst is significantly higher than the Tmax for the previous pentacoordinated catalysts. Without being bound by theory, this is significant in that in a reaction using a metathesis catalyst, if the part or article being prepared is a type of filled system (e.g., a system containing reinforcing fillers, fibers, beads, etc.), the filling material may act as a heat sink. With the previous pentacoordinated catalysts, post-curing was sometimes necessary due to the effect of the heat sink resulting from a filled system. ROMP polymerization in the presence of peroxide cross linking agents using pentacoordinated catalysts is discussed in U.S. Pat. No. 5,728,785, the contents of which are incorporated herein by reference. In contrast, the reactions using the inventive hexacoordinated catalysts generate significantly more internal heat. This high Tmax reduces the need for post cure. Additionally, even if peroxides or radicals are added to promote crosslinking, the degree of crosslinking in the part that uses the radical mechanism is increased in comparison to a part prepared using the previous pentacoordinated metathesis catalysts. Moreover, the half-life is dependent on the maximum temperature. Using the inventive catalysts, the half life is reduced substantially, and therefore less catalyst is needed, providing a significant commercial advantage. Without being bound by theory, the higher Tmax indicates that in a ROMP reaction, more rings are opened, and there is a better degree of cure. With a higher Tmax, the extractibles are almost to zero, indicating that almost every molecule that can be reacted is reacted. For example, the vinylidenes are advantageous in that they are more stable at higher temperatures than the alkylidenes. When the protected NHC (e.g., a saturated Imes ligand as described in U.S. Provisional Patent Application No. 60/288,680 and No. 60/278,311, the contents of each of which are incorporated herein by reference), is added to the reaction mixture, a dramatic increase in peak exotherm is seen. Additionally, the time to reach the peak is significantly reduced. A high peak exotherm means more catalyst is available for polymerization, indicating that the extractibles are close to zero. Accordingly, the inventive catalysts have better conversion, better properties, even in the presence of fillers and additives.
For the purposes of clarity, the specific details of the invention will be illustrated with reference to especially preferred embodiments. However, it should be appreciated that these embodiments and examples are for the purposes of illustration only and are not intended to limit the scope of the invention.